Insulin consists of a shorter A chain and a longer B chain. The two chains are held together with disulfide bonds. Invitro, insulin is processed from proinsulin a single polypeptide chain. The C chain is removed from proinsulin to form insulin.

A denaturation and renaturation experiment using urea and @- mercaptoethanol was carried out usin insulin. Less than 10% of the activity of insulin was recovered when the urea and 2 Mercaptoethanol were removed by dialysis. However, when the experiement was repeated with proinsulin, full activity was restored upon renaturation. Explain the above?

PLease find attached a very simple structure of proinsulin. Try to limit the answer to the diagram. But also try to explain in detail